Transmitting/receiving device and method for transmitting data in a radio network

ABSTRACT

In certain embodiments, an apparatus includes circuitry coupled to a switch between a first and second antenna of a device. The circuitry generates a first control signal for the switch to couple a transceiver of the device to the first antenna for transmission of a first data frame. The circuitry determines whether the transceiver has received, within a pre-determined time interval after transmission of the first data frame, a second data frame containing an acknowledgement message confirming successful receipt of the first data frame by another device. The circuitry generates, if the transceiver has not received the second data frame within the pre-determined time interval, a second control signal for the switch to couple the transceiver to the second antenna for re-transmission of the first data frame. An output line of the apparatus couples the circuitry to the switch and communicates the first or second control signal to the switch.

RELATED APPLICATION

This application is a continuation, under 35 U.S.C. §120, of U.S. patentapplication Ser. No. 13/046,557, filed 11 Mar. 2011, which claims thebenefit, under 35 U.S.C. §119(e), of U.S. Provisional Patent ApplicationNo. 61/313,317, filed 12 Mar. 2010, which are hereby incorporated byreference. This application also claims the benefit, under 35 U.S.C.§119(a), of German Patent Application No. 102010011343.3-35, also filed12 Mar. 2010.

TECHNICAL FIELD

This disclosure relates to a transmitting/receiving device fortransmitting data to another transmitting/receiving device.

BACKGROUND

In particular embodiments, a transceiver is a device that includes atransmitter and a receiver.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram.

FIG. 2 is a schematic flow chart.

DESCRIPTION OF EXAMPLE EMBODIMENTS

This disclosure relates to a transmitting/receiving device fortransmitting data to another transmitting/receiving device and a methodfor transmitting data to another transmitting/receiving device in aradio network.

German Patent Application No. DE 102005049931 (which U.S. Pat. No.7,596,365 claims priority to) describes a transmitting/receiving devicehaving a controller, which is designed to not relay a data frame to acontrol unit if it is determined that the data frame contains anacknowledgement message.

One problem addressed by this disclosure is that of optimally improvinga transmitting/receiving device for transmitting in a radio network.

According to particular embodiments, a transmitting/receiving device fortransmitting data to another transmitting/receiving device in a radionetwork is provided. The Transmitting/receiving device is preferablymonolithically integrated onto a semiconductor chip. Thetransmitting/receiving device for transmitting data is preferablyembodied so as to conform to IEEE communications industry standard IEEE802.15.4.

The transmitting/receiving device comprises a transmitting/receivingunit for connection to a first antenna and to a second antenna. Thetransmitting/receiving unit has a transmitting unit, which can beconnected to the first antenna and to the second antenna, fortransmitting data frames to the other transmitting/receiving device. Thetransmitting/receiving unit has a receiving unit for receiving dataframes from the other transmitting/receiving device.

The transmitting/receiving device has a control unit, connected to thetransmitting/receiving unit, for controlling the transmitting/receivingunit. The control unit is designed to instruct thetransmitting/receiving unit to transmit a first data frame.

The transmitting/receiving unit has a controller, which is connected tothe control unit and to the receiving unit and to the transmitting unit.The controller has a control output. The controller is designed tocontrol a switchover between the first antenna and the second antenna bysending out a first control signal assigned to the first antenna and asecond control signal assigned to the second antenna at the controloutput.

The controller is configured to send out the first control signal fortransmitting the first data frame.

The receiving unit of the transmitting/receiving unit is configured toreceive a second data frame.

The controller is designed to evaluate the second data frame and todetermine whether the second data frame was received within a predefinedtime interval after the transmission of the first data frame via thefirst antenna. The controller is also designed to determine whether thesecond data frame contains an acknowledgement message confirming thesuccessful receipt of the first data frame by the othertransmitting/receiving device.

The controller is configured to send out the second control signal for aswitchover between the antennas, and to retransmit the first data frameto the other transmitting/receiving device via the second antenna if asecond data frame does not contain the acknowledgement message withinthe predefined time interval.

Another problem addressed by this disclosure is that of providing anoptimally improved method for transmitting data.

According to particular embodiments, a method for transmitting data fromone transmitting/receiving device to another transmitting/receivingdevice in a radio network is provided.

In the method, a transmitting/receiving unit of thetransmitting/receiving device is instructed by a control unit of thetransmitting/receiving device, for example, via a command, to transmit afirst data frame.

In the method, a first control signal for switching a transmitting unitof the transmitting/receiving unit to a first antenna is sent out,wherein the first control signal is sent out by a controller of thetransmitting/receiving unit for transmitting the first data frame.

The transmitting unit of the transmitting/receiving unit transmits thefirst data frame to the other transmitting/receiving device.

The transmitting/receiving unit receives and evaluates a second dataframe.

The controller then determines whether the second data frame wasreceived via the first antenna within a predefined time interval afterthe transmission of the first data frame. The controller also determineswhether the second data frame contains an acknowledgement messageconfirming the successful receipt of the first data frame by the othertransmitting/receiving device.

When a second control signal is sent out, a switchover is made from thefirst antenna to the second antenna, and the first data frame isretransmitted via the second antenna to the other transmitting/receivingdevice if a second data frame does not contain the acknowledgementmessage within the predefined time interval.

Particular embodiments described in what follows relate both to thetransmitting/receiving device and to the method for transmitting datafrom one transmitting/receiving device to another transmitting/receivingdevice in a radio network.

In particular embodiments, it is provided that the control unit isconfigured to perform functions of the MAC layer. The MAC layer(medium-access-control) is an expansion of the OSI model proposed by theInstitute of Electrical and Electronics Engineers (IEEE). The data-linklayer (layer 2) in the OSI model is divided into the sublayers MediaAccess Control and Logical Link Control, with the MAC layer being thelower of the two.

In particular embodiments, the control unit is embodied to switch overto sleep mode after instructing the transmitting/receiving unit. Insleep mode, the control unit cannot perform any controlling function forcontrolling the transmitting/receiving unit. Therefore, thetransmitting/receiving unit is autonomous in terms of transmittingand/or receiving data frames. The transmitting/receiving unit ispreferably designed to wake the control unit out of sleep mode by meansof an interrupt signal.

In an operating mode, the control unit is preferably embodied to receivedata frames from the transmitting/receiving unit, which have beentransmitted, for example, by the other transmitting/receiving device.

In particular embodiments, the transmitting/receiving unit is configuredto perform functions of the physical layer (PHY) and the MAC layer of acommunications standard. The MAC layer, as a component of the data-linklayer, and the physical layer are defined, for example, by the OSImodel. The physical layer can also be called the bit transfer layer. Thetransmitting/receiving unit is preferably configured to perform thefunctions of the physical layer (PHY) and parts of the functions of theMAC layer, even when the control unit is in sleep mode.

In particular embodiments, the transmitting/receiving unit has a memoryfor storing an identification signal of a connected antenna. Theidentification signal is assigned to the first antenna. When two or moreantennas are physically present, the identification signal can be usedto define one of these antennas as the first antenna, via which thefirst data frame will first be transmitted. Therefore, theidentification signal can be used to select the first antenna, which inall probability will enable a transmission to the desired othertransmitting/receiving device. In addition, various additional(receiving) transmitting/receiving devices can be assigned differentidentification signals for different antennas.

In particular embodiments, the transmitting/receiving unit is preferablyconfigured to transmit the identification signal to the control unit.The transmitting/receiving unit first identifies the identificationsignal from the last successful transmission and stores it. Once thecontrol unit has been woken up and switched from sleep mode to operatingmode, the stored identification signal can be transmitted to the controlunit, for example, and, together with a node identification signal forthe other transmitting/receiving device, can be stored and optionallyevaluated in the control unit.

In particular embodiments, the control unit is preferably designed tostore the identification signal in the memory of thetransmitting/receiving unit. By storing said signal in the memory of thetransmitting/receiving unit, the control unit is able to specify whichphysically present antenna will first be used to transmit the first dataframe. Said first antenna can be determined from previous transmissions.

Particular embodiments are particularly advantageous alone or incombination. It is also possible to combine additional variants with oneanother. A number of possible combinations are described herein.However, these possible combinations of further variants are notintended as limiting.

In what follows, particular embodiments are specified in greater detailin reference to examples, illustrated in the drawings.

FIG. 1 shows one example of a WPAN data transmission system according toIEEE communications standard 802.15.4. It comprises twotransmitting/receiving devices 100, 200 in the form of stationary ormobile devices, which use radio signals to exchange information in awireless manner. For this purpose, the transmitting/receiving device 100is configured to transmit data to the other transmitting/receivingdevice 200 in the same radio network. The transmitting/receiving device100 is a full-function device, which is capable of assuming the functionof the WPAN coordinator. For example, the transmitting/receiving device200 can be a reduced-function device, which is assigned to thefull-function device 100 and is able to exchange data only with saiddevice. The transmitting/receiving devices 100, 200 comprise multiplecomponents, which are illustrated in functional blocks for thetransmitting/receiving device 100. In the interest of clarity, thefunctional blocks in the transmitting/receiving devices 200 are notshown in detail, although they may be present in said devices.

The transmitting/receiving device 100 of the embodiment example of FIG.1 can be connected via a connection 101 and via a high-frequency switch300 to a first antenna 310 and to a second antenna 320. Thetransmitting/receiving device 100 is integrated, for example, as anintegrated circuit on a semiconductor chip. As an alternative to theembodiment example of FIG. 1, the high-frequency switch 300 and/or thefirst antenna 310 and/or the second antenna 320 can be integratedtogether with the transmitting/receiving device 100 on the samesemiconductor chip or together on a circuit carrier, such as a circuitboard.

A transmitting/receiving unit 150 of the transmitting/receiving device100 can be connected to the first antenna 310 and to the second antenna320 via the connection 101. The transmitting/receiving unit 150 can alsobe called transceiver TRX. The transmitting/receiving unit 150 comprisesa transmitter (TX) 121, which can be connected to the first antenna 310and to the second antenna 320, for transmitting data frames D1, D1′ tothe other transmitting/receiving device 200. The transmitter 121converts the data stream to be transmitted according to IEEE 802.15.4 toa radio signal to be broadcast via antenna 310 or 320. If thetransmission will take place, for example, in the ISM frequency band at2.4 GHz, the data stream to be transmitted is first converted tofour-bit symbols, and these are converted to sequential, symbolvalue-specific PN (Pseudo Noise) sequences. In this case, the digitaldata, which will be modulated by the transmitting unit 121 to a carriersignal and emitted at the output of the transmitting unit 12 for one ofthe two antennas 310, 320, are present at the input of the transmitter121. Thus the transmitter 121 performs specific functions at the levelof the physical layer (PHY). The first data frame D1 to be transmittedis thereby converted from a MAC frame to a longer PHY frame, since, forexample, a synchronization header precedes it, so as to enablesynchronization to the data stream at the receiver end.

The transmitting/receiving device 100 further comprises a receiver (RX)122, for receiving data frames D2 from the other transmitting/receivingdevice 200. In the embodiment example of FIG. 1, data are transmittedand received in conformance with the communications standard IEEE802.15.4. The receiver 122 converts a radio signal, generated accordingto IEEE 802.15.4 and received from an antenna 310, 320, ideally withouterrors, according to the prescriptions of said standard, into thetransmitted data by filtering the received radio signal, transforming itto the base band, demodulating it, and detecting the data (deciding),for example. Thus the receiver 122 also performs specific functions ofthe PHY layer. The received second data frame D2 in this case isconverted from a PHY frame to a shorter MAC frame, since, for example,it lacks the synchronization header.

The transmitting/receiving device 100 of the embodiment example of FIG.1 has a control unit 160, connected to the transmitting/receiving unit150, for controlling the transmitting/receiving unit 150. The controlunit 160 is embodied, for example, as a microcontroller. In addition,the transmitting/receiving unit 150 is embodied, for example, as an ASIC(application specific integrated circuit). Transmitting/receiving unit150 and control unit 160 are preferably embodied as a single integratedcircuit.

The transmitting/receiving unit 150 and the control unit 160 aresupplied with power by an energy supply unit in the form of a battery,for example, which is not shown in FIG. 1, and which may also supplypower to additional components, such as sensors, actuators, etc.

The control unit 160 is designed to instruct the transmitting/receivingunit 150 of “its” transmitting/receiving device 100 to transmit a firstdata frame D1 to the other transmitting/receiving device 200. Thetransmitting/receiving unit 150 has a controller 120 (EVAL), which isconnected to the control unit 160 and to the receiver 122, and, in theembodiment example of FIG. 1, to the transmitter 121. The controller 120is designed to receive from the control unit 160, for example, by meansof a command S and/or by transmission of the first data frame D1, aninstruction to transmit the first data frame D1 to the othertransmitting/receiving device 200. It is further designed to transmitthe first data frame D1 in the form of a MAC frame to the transmitter121 and to instruct said transmitter to transmit D1, as is indicatedschematically in FIG. 1 by arrows. Upon receiving such an instruction,the transmitting/receiving unit 150 of the transmitting/receiving device100 then transmits the first data frame D1 to the othertransmitting/receiving device 200.

If the other transmitting/receiving device 200 transmits a second dataframe D2 back to the transmitting/receiving device 100, the second dataframe D2 is received by the transmitting/receiving unit 150 of thetransmitting/receiving device 100 and, if applicable, is relayed to thecontrol unit 160 of the transmitting/receiving device 100, to beevaluated by the control unit 160. For this purpose, the controller 120is advantageously configured to receive second data frames D2 in theform of MAC frames from the receiver 122 and, if applicable, to relaythese to the control unit 160. In FIG. 1, this is illustrated by thearrows between controller 120 and receiver 122 and by the arrow labeled“D2” between controller 120 and control unit 160.

The transmitting/receiving unit 150 is designed to perform the functionsof the physical layer of the communications standard. The control unit160 is designed to perform at least a majority of the functions of theMAC (medium access control) layer of the communications standard. Inaddition to the specified functions at the level of the physical layer(PHY), the transmitting/receiving unit 150 also performs a number offunctions specified at the level of the MAC layer of the communicationsstandard—IEEE 802.15.4 in the embodiment example of FIG. 1. This makesit possible to use finite state machines to perform time-criticalfunctions, which are actually defined at a higher level, in the physicallayer (PHY) (bit transfer layer), without requiring the control unit160—for example, a microcontroller—for this purpose. The control unit160 is then charged “only” with the remaining functions of the MAC layerand, if applicable, with functions of higher layers. For this purpose,the control unit 160 is embodied, for example, to receive and evaluatesecond data frames D2 from the transmitting/receiving unit 150.

In addition, the controller 120 has a control output 102 for controllinga switchover between the first antenna 310 and the second antenna 320.To implement this, the controller sends out a first control signal SW1(for example, an H potential) assigned to the first antenna 310 and asecond control signal SW2 (for example, an L potential) assigned to thesecond antenna, at the control output 102. For the switchover, in FIG.1, a high-frequency switch 300 is provided, to which the first antenna310 and the second antenna 320 are connected.

In what follows, it is assumed that the first antenna is the antenna viawhich the first data frame D1 is first transmitted. In contrast, thesecond antenna is the antenna via which the first data frame D1′ isfirst transmitted thereafter. The physical connection has no bearing onthe identification as first or second antenna.

The controller 120 is configured to first send out the first controlsignal SW1 for the first-time transmission of the first data frame D1.The first data frame D1 requires an acknowledgement message ACK(ACKnowledgement)—which can also be called a receipt—from the othertransmitting/receiving device 200 when said device receives the firstdata frame D1.

In particular embodiments, the transmitting/receiving unit 150 takes onfunctionalities specified at the MAC level of evaluating received seconddata frames D2 once the first data frame D1 has been transmitted. Inthis, the controller 120 evaluates a second data frame D2 received bythe receiver 122, within a predefined time interval T1—between 150 μsand 500 μs, for example—after the transmission of the first data frameD1. In this evaluation, the controller 120 checks to see whether thesecond data frame D2 contains an acknowledgement message ACK confirmingsuccessful receipt of the first data frame D1 by the othertransmitting/receiving device 200.

If it is determined during this check that D2 contains theacknowledgement message ACK, the controller 120 will not relay thesecond data frame D2 to the control unit 160, for example, by openingthe switch element 125. This allows the control unit 160, which toconserve energy has at least two operating modes that consume differentamounts of energy, to switch as quickly as possible to a low-energy“sleep mode,” specifically as soon as it has instructed thetransmitting/receiving unit 150 to transmit the first data frame D1.

The control unit 160 assumes that the data frame D1 will be successfullyreceived by the second transmitting/receiving device 200.

The controller 120 is configured to use an evaluation unit 123 toevaluate a second data frame D2, received by the receiver 122 within thepredefined time interval T1 after the transmission of the first dataframe D1 via the first antenna 310. For this purpose, the evaluationunit 123 is connected to the receiver 122. The controller 120 determineswhether the second data frame D2 contains an acknowledgement message ACKconfirming the successful receipt of the first data frame D1 by theother transmitting/receiving device 200.

If the evaluation by the evaluation unit 123 of the controller 120 showsthat within the predefined time interval T1 no second data frame D2contains the acknowledgement message ACK, the controller 120 isconfigured to send out the second control signal SW2 for switching overbetween the antennas 310, 320, and for retransmitting the first dataframe D1′ to the other transmitting/receiving device 200 via the secondantenna 320. There are several possible reasons why the acknowledgementmessage ACK would not be contained in a data frame D2. For example, thefirst data frame D1 may not have been received by the othertransmitting/receiving device 200 due to inadequate transmissionconditions.

In the example of FIG. 1, the controller 120 is configured to call for aretransmission of the first data frame D1, D1′ without instruction bythe control unit 160, wherein after each retransmission, a check is madeto determine whether a received second data frame D2 contains anacknowledgement message ACK. In this, the transmitter 121 retransmitsthe first data frame D1′ to the other transmitting/receiving device 200,if no second data frame D2 contains the acknowledgement message ACKwithin the predefined time interval T1. In addition, the controller 120is configured to switch over between the antennas 310 and 320 for eachretransmission. During the retransmission of the first data frame D1′the control unit 160 remains in sleep mode.

The controller 120 has a memory 124 (MEM). The first data frame D1 isstored in the memory 124 for the retransmission. The controller 120 isconfigured to store an identification signal for an antenna for thecontrol signal SW1, SW2 in the memory 124. The identification signal isassigned to the antenna (310 or 320), for example, via which the firstdata frame D1 was successfully transmitted—as proven by the receivedacknowledgement message ACK. Once the control unit 160 has been woken upand switched from sleep mode to operating mode, the identificationsignal can be transmitted to the control unit 160.

The controller 120 preferably has a repetition counter, which counts thenumber of times the first data frame D1 is transmitted. If a count fromthe repetition counter exceeds a threshold value, the control unit 160is woken up from sleep mode by an interrupt signal IR and is switched tothe operating mode, and the controller 120 transmits status informationabout the exceeded threshold to the control unit 160. Thus, thecontroller 120 is configured to inform the control unit 160, forexample, by the interrupt IR, only if an acknowledgement message ACK isnot contained in a received second data frame D2 even after a predefinednumber of retransmissions of the first data frame D1. Saidretransmissions are not called for individually by the control unit 160,and instead, the repeated transmissions of the first data frame D1 arecontrolled autonomously by the controller 120. This allows the controlunit 160 to remain in sleep mode.

The control unit 160 is designed to leave the sleep mode when itreceives the interrupt IR from the controller 120. The controller 120 isset up to inform the control unit 160 by means of the interrupt IR if,within the predefined time interval T1, no second data frame D2 isreceived, or if it is determined that each second data frame D2 does notcontain the acknowledgement message ACK.

The first data frame D1 is transmitted first via the first antenna 310.The first antenna 310 is defined in this case by an assignment to one oftwo physically present antennas. For this purpose, the identificationsignal of one of the antennas is stored in the memory 124. For example,the identification signal defines one of the antennas as the defaultfirst antenna 310. The controller 120 or the control unit 160 ispreferably configured to establish the identification signal for thefirst antenna 310 in the memory 124 by writing the identificationsignal. For example, the control unit 160 or the controller 120 usesprevious transmissions of the first data frame D1, confirmed by anacknowledgement message ACK, to identify said antenna as the firstantenna 310. In this case, a transmission via the same antenna canprobably be performed with the same favorable transmission conditions asthe previous transmission. This applies particularly to stationarytransmitting/receiving devices.

In particular embodiments, the identification signal stored in thememory 124 as the signal for the first antenna 310 is the signal for theantenna for which an open transmission channel was most recentlyidentified—for example, by means of a CCA process.

Advantageously, the control unit 160 or the controller 120 is configuredto evaluate incoming signals of the two antennas from a received seconddata frame D2, in order to identify one of the antennas for the bestreception. From said evaluation of the incoming signals, the antenna fora subsequent transmission of the first data frame D1 is also chosen, andits identification signal is stored in the memory 124 for specifying thefirst antenna 310.

FIG. 2 shows a schematic flow chart illustrating the sequence of stepsin a method. The sequence of steps can be implemented, for example,using a finite state machine as the hardware of the controller 120.

In a first step 1, a transmitting mode TRX_STATE is started. In thismode, a control unit 160—for example, a microcontroller—instructs atransmitting/receiving unit 150, by means of a command S, to transmit afirst data frame D1. Also in the first step 1, an identification signalof an antenna as the first antenna 310 can be transmitted by the controlunit 160 to the transmitting/receiving unit 150. After giving theinstruction, the control unit 160 can switch to a sleep mode in thefirst step 1. The subsequent steps are a component of the MAC layer andthe bit transfer layer and are performed, up to step 20, exclusively bythe transmitting/receiving unit 150.

In the second step 2, a controller 120 of the transmitting/receivingunit 150 sets a counter value frame_rctr to zero. In the subsequent step3, a check is made to determine whether a transmission of the first dataframe D1 is possible, or whether, for example, at that moment a seconddata frame D2 is being received. This check is made repeatedly until atransmission TX of the first data frame D1 is possible. In the next step4, the transmitting/receiving unit 150 is placed in “active transmittingmode” status.

In the subsequent steps 5, 6, 7, 8 and 9 of group 50, checks are made todetermine whether a transmission channel is open for transmitting thefirst data frame D1. For this purpose, the controller 120 is configuredto instruct a receiver 122 of the transmitting/receiving unit 150 tocheck whether the transmission channel intended for transmission of thefirst data frame D1 is occupied. The controller 120 is configured toinstruct a transmitter 121 of the transmitting/receiving unit 150 totransmit the first data frame D1 only if the check shows that theintended transmission channel is open.

One example of a method of this type is the CSMA/CA method (carriersense multiple access/collision avoidance), which can be used, forexample, in communications standard IEEE 802.15.4. For collisionavoidance when accessing the radio interface, a CSMA/CA algorithm isused. In step 5, a check is first made to determine whether the maximumnumber MAX_CSMA of repetitions of the CSMA/CA process is below athreshold value, which in the embodiment example of FIG. 2 is seven. Instep 6, a count value csma_rctr is set to zero.

Before transmitting, the transmitting/receiving unit 150 checks todetermine whether another device is currently transmitting on theselected channel, by measuring a signal from the antenna. In step 7, aCCA process (clear channel assessment) with the CCA modes 1, 2 or 3 inthe communications standard IEEE 802.15.4 is used for this purpose. Alsoin step 7, the count value csma_rctr is increased by one to csma_rctr+1.If the channel is open in step 8, transmission of the first data frameD1 begins in step 11. If the channel is not open, a check is made instep 9 to determine whether the count value csma_rctr is greater thanthe maximum number MAX_CSMA. If the count value CSMA_rctr is notgreater, the device will expect a random time interval in step 7 andwill perform a repeated “channel open test” in step 7, wherein the countvalue CSMA_rctr is again increased by one. If the count value CSMA_rctris greater than the maximum number MAX_CSMA, a status message isgenerated in step 10, which is relayed in the form of an interrupt IR tothe control unit 160 in step 20. The current transmitting/receivingstatus TRX_state is determined similarly in step 21.

Step 11 is the first step of group 60. In step 11, the first data frameD1 is transmitted via the first antenna 310 and a frame counterframe_rctr is increased by one to frame_rctr+1. To control thetransmission of the first data frame D1 via the first antenna, thecontroller 120 sends out a first control signal SW1. If the first dataframe D1 does not require an acknowledgement message ACK, then afterstep 12, in step 16 a, a status is established, which is transmitted bymeans of the interrupt IR in step 20 to the control unit 160.

In step 13, a second data frame D2 is received and checked to determinewhether the second data frame D2 contains the acknowledgement messageACK. It is also checked to determine whether a specific time t ofreceipt of the acknowledgement message ACK lies within the time intervalT1. If both apply, a check is made in step 14 to determine whether theacknowledgement message ACK is valid. In the next step 15, a check ismade to determine whether there are additional data called up fortransmission, and the status is set accordingly in step 16, or 16 a.

If no second data frame D2 with an acknowledgement message ACK isreceived in step 13, or if the time t is already past the time intervalT1, or if it is determined in step 14 that the acknowledgement messageACK is invalid, then step 17 will follow. In step 17 a check is made todetermine whether the frame counter value frame_rctr is greater than amaximum value MAX_FRAME for the transmitted frame. If the maximum valueMAX_FRAME is exceeded, in step 18 the status will be set to “noacknowledgement message ACK received” and in step 20 this will betransmitted to the control unit 160 by means of interrupt IR.

In contrast, if the maximum value MAX_FRAME is not reached in step 17,then in step 19 the second antenna 320 will be actuated, by thecontroller 120 sending out the second control signal SW2. Steps 5, 6, 7,8 and 11 can then follow in turn, wherein in step 11 the first dataframe D1′ is transmitted via the second antenna 320. If the processproceeds through steps 12, 13/14 and 17 and again reaches step 19, aswitchover will again be made to the first antenna 310 by sending outthe first control signal SW1. In step 19, each time the series of steps5, 6, 7, 8, 11, 12, 13, 14, 17 and 19 is performed, a switchover is madebetween the antennas 310, 320, in other words, from the first antenna310 to the second antenna 320 or from the second antenna 320 to thefirst antenna 310. Rather than the embodiment examples illustrated inFIGS. 1 and 2 containing two antennas 310, 320, three or more antennasmay also be provided, between which switchovers are made in a predefinedsequence, for example.

With the example of FIG. 1, with various antenna positions of the firstantenna 310 and the second antenna 320, the advantage may be achievedthat a better transmission channel can be used when destructiveinterference leads to connection gaps in the transmission path for aspecific antenna position. With the example of FIG. 1, however, theamount of power consumed is not substantially increased and remainssubstantially unchanged as compared with a single antenna. This isachieved by the fact that switching between the antennas requires nointeraction with the control unit 160, which can remain in sleep modeeven during switchovers between the antennas 310, 320.

This disclosure is not limited to the variants illustrated in FIGS. 1and 2. For example, it is possible to provide three or more antennas,and to switch between them. It is also possible to switch betweenantennas 310, 320 for receiving. The functionality of the circuitaccording to FIG. 1 can be used to particular advantage for a universalradio system according to the industry standard IEEE 802.15.4 oralternatively IEEE 802.11 or alternatively IEEE 802.15.1.

The following is a list of reference symbols and numbers in FIGS. 1 and2, provided for example illustration purposes only and not by way oflimitation:

-   -   1-21 Process steps    -   100, 200 Transmitting/receiving device    -   101 Connection    -   102 Control output    -   120 Controller    -   121 Transmitter    -   122 Receiver    -   123 Evaluation unit    -   124 Memory    -   125 Switch element    -   150 Transmitting/receiving unit, circuit    -   160 Control unit    -   300 High-frequency switch    -   310, 320 Antenna    -   D1, D1′, D2 Data frame    -   S Command    -   ACK Acknowledgement message    -   IR Interrupt, interrupt signal    -   SW1, SW2 Control signal    -   T1 Time interval

What is claimed is:
 1. An apparatus comprising: circuitry coupled to aswitch between a first antenna of a device and a second antenna of thedevice, the switch being configured to couple a transceiver of thedevice to the first antenna or the second antenna, the circuitry beingconfigured to: generate a first control signal for the switch to couplethe transceiver to the first antenna for transmission of a first dataframe by the transceiver via the first antenna; determine whether thetransceiver has received, within a pre-determined time interval afterthe transmission of the first data frame, a second data frame containingan acknowledgement message confirming successful receipt of the firstdata frame by another device; and generate, if the transceiver has notreceived within the pre-determined time interval after the transmissionof the first data frame the second data frame, a second control signalfor the switch to couple the transceiver to the second antenna forretransmission of the first data frame by the transceiver via the secondantenna; and an output line coupling the circuitry to the switch andbeing configured to communicate the first or second control signal tothe switch.
 2. The apparatus of claim 1, wherein the circuitry comprisesa controller and a control unit, the control unit having at least anoperating mode and a sleep mode and configured to, while in theoperating mode, send an instruction to the controller for thetransceiver to transmit the first data frame and then enter the sleepmode.
 3. The apparatus of claim 2, wherein the controller is configuredto, without waking the control unit from the sleep mode, generate, ifthe transceiver has not received within the pre-determined time intervalafter the transmission of the first data frame the second data frame,the second control signal for the switch to couple the transceiver tothe second antenna for re-transmission of the first data frame by thetransceiver via the second antenna.
 4. The apparatus of claim 2, whereinthe controller is further configured to: receive an instruction for thetransceiver to transmit the first data frame; and generate, if thetransceiver has not received within the pre-determined time intervalafter re-transmission of the first data frame by the transceiver via thesecond antenna the second data frame, an interrupt signal to the controlunit to exit sleep mode.
 5. The apparatus of claim 1, wherein thecircuitry is further configured to: set a repetition counter to acounter value of zero; increase the counter value by one when thetransceiver transmits or re-transmits the first data frame; determinewhether the counter value has reached a pre-determined threshold value;and change, if the counter value has reached the pre-determinedthreshold value, a transceiver status to indicate that the transceiverhas not received a second data frame containing an acknowledgementmessage confirming successful receipt of the first data frame by anotherdevice.
 6. The apparatus of claim 1, wherein the circuitry is furtherconfigured to: determine which one of two or more physical antennae ofthe device more recently had an open transmission channel; assign anidentification signal to the one of the two or more physical antennae ofthe device that more recently had an open transmission channel; storethe identification signal; and designate as the first antenna the one ofthe two or more physical antennae that more recently had an opentransmission channel.
 7. The apparatus of claim 1, wherein the device isconfigured to transmit the first data frame and the second data frameaccording to the Institute of Electrical and Electronics Engineers802.15.4 standard.
 8. A method comprising: generating, using circuitrycoupled to a switch between a first antenna of a device and a secondantenna of the device, the switch being configured to couple atransceiver to the first antenna or the second antenna, a first controlsignal for the switch to couple the transceiver to the first antenna fortransmission of a first data frame by the transceiver via the firstantenna; determining, using the circuitry, whether the transceiver hasreceived within a predetermined time interval after the transmission ofthe first data frame a second data frame containing an acknowledgementmessage confirming successful receipt of the first data frame by anotherdevice; and generating, using the circuitry and if the transceiver hasnot received within the predetermined time interval after thetransmission of the first data frame the second data frame, a secondcontrol signal for the switch to couple the transceiver to the secondantenna for retransmission of the first data frame by the transceivervia the second antenna.
 9. The method of claim 8, wherein the circuitrycomprises a controller and a control unit, the control unit having atleast an operating mode and a sleep mode and configured to, while in theoperating mode, send an instruction to the controller for thetransceiver to transmit the first data frame and then enter the sleepmode.
 10. The method of claim 9, comprising generating, without wakingthe control unit from the sleep mode and if the transceiver has notreceived within the predetermined time interval after the transmissionof the first data frame the second data frame, the second control signalfor the switch to couple the transceiver to the second antenna forretransmission of the first data frame by the transceiver via the secondantenna.
 11. The method of claim 9, further comprising: receiving, atthe controller, an instruction for the transceiver to transmit the firstdata frame; and generating, if the transceiver has not received withinthe pre-determined time interval after re-transmission of the first dataframe by the transceiver via the second antenna the second data frame,an interrupt signal to the control unit to exit sleep mode.
 12. Themethod of claim 8, further comprising: setting a repetition counter to acounter value of zero; increasing the counter value by one when thetransceiver transmits or re-transmits the first data frame; determiningwhether the counter value has reached a pre-determined threshold value;and changing, if the counter value has reached the pre-determinedthreshold value, a transceiver status to indicate that the transceiverhas not received a second data frame containing an acknowledgementmessage confirming successful receipt of the first data frame by anotherdevice.
 13. The method of claim 8, further comprising: determining whichone of two or more physical antennae of the device more recently had anopen transmission channel; assigning an identification signal to the oneof the two or more physical antennae of the device that more recentlyhad an open transmission channel; storing the identification signal; anddesignating as the first antenna the one of the two or more physicalantennae that more recently had an open transmission channel.
 14. Themethod of claim 8, wherein the device is configured to transmit thefirst data frame and the second data frame according to the Institute ofElectrical and Electronics Engineers 802.15.4 standard.
 15. One or morecomputer-readable non-transitory storage media embodying logic that isconfigured when executed to: generate a first control signal for aswitch between a first antenna of a device and a second antenna of thedevice to couple a transceiver to the first antenna for transmission ofa first data frame by the transceiver via the first antenna, the switchbeing configured to couple the transceiver to the first antenna or thesecond antenna; determine whether the transceiver has received within apre-determined time interval after the transmission of the first dataframe a second data frame containing an acknowledgement messageconfirming successful receipt of the first data frame by another device;and generate, if the transceiver has not received within thepre-determined time interval after the transmission of the first dataframe the second data frame, a second control signal for the switch tocouple the transceiver to the second antenna for re-transmission of thefirst data frame by the transceiver via the second antenna.
 16. Themedia of claim 15, wherein the logic is further configured to receive aninstruction from a control unit to transmit the first data frame, thecontrol unit having at least an operating mode and a sleep mode andconfigured to, while in the operating mode, send an instruction to acontroller for the transceiver to transmit the first data frame and thenenter the sleep mode.
 17. The media of claim 16, wherein the logic isconfigured to generate, without waking the control unit from the sleepmode and if the transceiver has not received within the pre-determinedtime interval after the transmission of the first data frame the seconddata frame, the second control signal for the switch to couple thetransceiver to the second antenna for re-transmission of the first dataframe by the transceiver via the second antenna.
 18. The media of claim16, wherein the logic is further configured to generate, if thetransceiver has not received within the pre-determined time intervalafter retransmission of the first data frame by the transceiver via thesecond antenna the second data frame, an interrupt signal to the controlunit to exit sleep mode.
 19. The media of claim 15, wherein the logic isfurther configured to: set a repetition counter to a counter value ofzero; increase the counter value by one when the transceiver transmitsor re-transmits the first data frame; determine whether the countervalue has reached a pre-determined threshold value; and change, if thecounter value has reached the pre-determined threshold value, atransceiver status to indicate that the transceiver has not received asecond data frame containing an acknowledgement message confirmingsuccessful receipt of the first data frame by another device.
 20. Themedia of claim 15, wherein the logic is further configured to: determinewhich one of two or more physical antennae of the device more recentlyhad an open transmission channel; assign an identification signal to theone of the two or more physical antennae of the device that morerecently had an open transmission channel; store the identificationsignal; and designate as the first antenna the one of the two or morephysical antennae that more recently had an open transmission channel.